<template>
  <div class="spec-preview" @mousemove="mousemove">
    <img :src="skuImageList[defaultImgIndex]?.imgUrl" />
    <div class="event" ref="event"></div>
    <div class="big">
      <img :src="skuImageList[defaultImgIndex]?.imgUrl" ref="bigImg" />
    </div>
    <div class="mask" ref="mask"></div>
  </div>
</template>

<script>
export default {
  name: "Zoom",
  props: ["skuImageList"],
  data(){
    return {
      defaultImgIndex:0,
    }
  },
  mounted(){
    this.$bus.$on("defaultImg",(index)=>{
      this.defaultImgIndex = index;
    })
  },
  methods: {
    mousemove(e) {
      const event = this.$refs.event;
      const mask = this.$refs.mask;
      const bigImg = this.$refs.bigImg;
      const mouseOffset = {
        x: e.offsetX,
        y: e.offsetY,
      };
      const maskHalf = {
        x: this.$refs.mask.offsetWidth / 2,
        y: this.$refs.mask.offsetHeight / 2,
      };
      const maskLocation = {
        x: mouseOffset.x - maskHalf.x,
        y: mouseOffset.y - maskHalf.y,
      };

      if (maskLocation.x < 0) {
        maskLocation.x = 0;
      } else if (maskLocation.x > event.clientWidth - mask.offsetWidth) {
        maskLocation.x = event.clientWidth - mask.offsetWidth;
      }

      if (maskLocation.y < 0) {
        maskLocation.y = 0;
      } else if (maskLocation.y > event.clientHeight - mask.offsetHeight) {
        maskLocation.y = event.clientHeight - mask.offsetHeight;
      }

      mask.style.left = maskLocation.x + "px";
      mask.style.top = maskLocation.y + "px";

      bigImg.style.left = -maskLocation.x * 2 + "px";
      bigImg.style.top = -maskLocation.y * 2 + "px";
    },
  },
};
</script>

<style lang="less">
.spec-preview {
  position: relative;
  width: 400px;
  height: 400px;
  border: 1px solid #ccc;

  img {
    width: 100%;
    height: 100%;
  }

  .event {
    width: 100%;
    height: 100%;
    position: absolute;
    top: 0;
    left: 0;
    z-index: 998;
  }

  .mask {
    width: 50%;
    height: 50%;
    background-color: rgba(0, 255, 0, 0.3);
    position: absolute;
    left: 0;
    top: 0;
    display: none;
  }

  .big {
    width: 100%;
    height: 100%;
    position: absolute;
    top: -1px;
    left: 100%;
    border: 1px solid #aaa;
    overflow: hidden;
    z-index: 998;
    display: none;
    background: white;

    img {
      width: 200%;
      max-width: 200%;
      height: 200%;
      position: absolute;
      left: 0;
      top: 0;
    }
  }

  .event:hover ~ .mask,
  .event:hover ~ .big {
    display: block;
  }
}
</style>
